[PATCH 3/5] Implement TFRC-SP calc of mean length of loss

[Ivo Calado <ivocalado@embedded.ufcg.edu.br>]

Implement TFRC-SP calc of mean length of loss intervals accordingly to
section 3 of RFC 4828

Changes:
- Modify tfrc_sp_lh_calc_i_mean header, now receiving the current ccval,
so it can determine
   if a loss interval is too recent
- Consider number of losses in each loss interval
- Only consider open loss interval if it is at least 2 rtt old
- Changes function signatures as necessary

Signed-off-by: Ivo Calado, Erivaldo Xavier, Leandro Sales
<ivocalado@embedded.ufcg.edu.br>, <desadoc@gmail.com>,
<leandroal@gmail.com>

Index: dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.c
=================================--- dccp_tree_work4.orig/net/dccp/ccids/lib/loss_interval_sp.c
2009-09-03 23:00:24.000000000 -0300
+++ dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.c 2009-09-03
23:00:31.000000000 -0300
@@ -67,10 +67,11 @@
}
}

-static void tfrc_sp_lh_calc_i_mean(struct tfrc_loss_hist *lh)
+static void tfrc_sp_lh_calc_i_mean(struct tfrc_loss_hist *lh, __u8
curr_ccval)
{
u32 i_i, i_tot0 = 0, i_tot1 = 0, w_tot = 0;
int i, k = tfrc_lh_length(lh) - 1; /* k is as in rfc3448bis, 5.4 */
+ u32 losses;

if (k <= 0)
return;
@@ -78,6 +79,15 @@
for (i = 0; i <= k; i++) {
i_i = tfrc_lh_get_interval(lh, i);

+ if (SUB16(curr_ccval,
+     tfrc_lh_get_loss_interval(lh, i)->li_ccval) <= 8) {
+
+ losses = tfrc_lh_get_loss_interval(lh, i)->li_losses;
+
+ if (losses > 0)
+ i_i = div64_u64(i_i, losses);
+ }
+
if (i < k) {
i_tot0 += i_i * tfrc_lh_weights[i];
w_tot  += tfrc_lh_weights[i];
@@ -87,6 +97,11 @@
}

lh->i_mean = max(i_tot0, i_tot1) / w_tot;
+ BUG_ON(w_tot = 0);
+ if (SUB16(curr_ccval, tfrc_lh_get_loss_interval(lh, 0)->li_ccval) > 8)
+ lh->i_mean = max(i_tot0, i_tot1) / w_tot;
+ else
+ lh->i_mean = i_tot1 / w_tot;
}

/**
@@ -127,7 +142,7 @@
return;

cur->li_length = len;
- tfrc_sp_lh_calc_i_mean(lh);
+ tfrc_sp_lh_calc_i_mean(lh, dccp_hdr(skb)->dccph_ccval);
}

/* RFC 4342, 10.2: test for the existence of packet with sequence number
S */
@@ -148,7 +163,8 @@
bool tfrc_sp_lh_interval_add(struct tfrc_loss_hist *lh,
     struct tfrc_rx_hist *rh,
     u32 (*calc_first_li)(struct sock *),
-      struct sock *sk)
+      struct sock *sk,
+      __u8 ccval)
{
struct tfrc_loss_interval *cur = tfrc_lh_peek(lh);
struct tfrc_rx_hist_entry *cong_evt;
@@ -217,7 +233,7 @@
if (lh->counter > (2*LIH_SIZE))
lh->counter -= LIH_SIZE;

- tfrc_sp_lh_calc_i_mean(lh);
+ tfrc_sp_lh_calc_i_mean(lh, ccval);
}

return true;
Index: dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.h
=================================--- dccp_tree_work4.orig/net/dccp/ccids/lib/loss_interval_sp.h
2009-09-03 23:00:24.000000000 -0300
+++ dccp_tree_work4/net/dccp/ccids/lib/loss_interval_sp.h 2009-09-03
23:00:31.000000000 -0300
@@ -73,7 +73,8 @@
extern bool tfrc_sp_lh_interval_add(struct tfrc_loss_hist *,
    struct tfrc_rx_hist *,
    u32 (*first_li)(struct sock *),
-     struct sock *);
+     struct sock *,
+     __u8 ccval);
extern void tfrc_sp_lh_update_i_mean(struct tfrc_loss_hist *lh,
     struct sk_buff *);
extern void tfrc_sp_lh_cleanup(struct tfrc_loss_hist *lh);
Index: dccp_tree_work4/net/dccp/ccids/lib/packet_history_sp.c
=================================--- dccp_tree_work4.orig/net/dccp/ccids/lib/packet_history_sp.c
2009-09-03 23:00:24.000000000 -0300
+++ dccp_tree_work4/net/dccp/ccids/lib/packet_history_sp.c 2009-09-03
23:00:31.000000000 -0300
@@ -369,7 +369,8 @@
/*
* Update Loss Interval database and recycle RX records
*/
- new_event = tfrc_sp_lh_interval_add(lh, h, first_li, sk);
+ new_event = tfrc_sp_lh_interval_add(lh, h, first_li, sk,
+ dccp_hdr(skb)->dccph_ccval);
__three_after_loss(h);

} else if (dccp_data_packet(skb) && dccp_skb_is_ecn_ce(skb)) {
@@ -378,7 +379,8 @@
* the RFC considers ECN marks - a future implementation may
* find it useful to also check ECN marks on non-data packets.
*/
- new_event = tfrc_sp_lh_interval_add(lh, h, first_li, sk);
+ new_event = tfrc_sp_lh_interval_add(lh, h, first_li, sk,
+ dccp_hdr(skb)->dccph_ccval);
/*
* Also combinations of loss and ECN-marks (as per the warning)
* are not supported. The permutations of loss combined with or